The objective of this research proposal is the elucidation of the structure and mechanism of synthesis of small, RNA-containing viruses with the expectation that many of the important results will be relevant to viruses in general and will contribute to an understanding of the interaction of viruses with their host cells. We will use standard methods such as centrifugation, electrophoresis, radioactive labeling, in vitro nucleic acid and protein synthesis and sequencing of proteins and nucleic acids. We will emphasize work with viruses whose genome is messenger RNA, in particular, the viruses Q beta, BMV, Nodamura, SBMV and their relatives.